Patchwork [002/002] de2104x: support for systems lacking cache coherence

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Submitter Risto Suominen
Date Feb. 11, 2009, 12:18 p.m.
Message ID <46e1c7760902110418n276de9b2xa2169839b9e25dc0@mail.gmail.com>
Download mbox | patch
Permalink /patch/22913/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Risto Suominen - Feb. 11, 2009, 12:18 p.m.
2009/2/11 David Miller <davem@davemloft.net>:
>
> I think the pci_alloc_consistent() implementation for your particular
> platform should be fixed instead :-)
>
Looks like it works as expected with 2.6.24. This patch is all that is needed.

Still I think that my first solution was beautiful in its simplicity
:) (and usable with older kernels)

Risto

Allow setting NOT_COHERENT_CACHE explicitly.

Signed-off-by: Risto Suominen <Risto.Suominen@gmail.com>
---
The testing is done on kernel version 2.6.24.

--- a/arch/powerpc/platforms/powermac/Kconfig.org	2008-01-25
00:58:37.000000000 +0200
+++ b/arch/powerpc/platforms/powermac/Kconfig	2009-02-10
17:44:24.000000000 +0200
@@ -18,4 +18,10 @@ config PPC_PMAC64
 	select PPC_970_NAP
 	default y

-
+config NOT_COHERENT_CACHE
+	bool "Incoherent cache"
+	default n
+	help
+	  Setting this option may be necessary for avoiding cache-related
+	  problems with some network cards on some platforms. An example is
+	  2104x and PowerMac 5500.
Risto Suominen - Feb. 11, 2009, 12:31 p.m.
As an interesting side effect, the patch caused my mesh module to stop
working. It crashes.

Risto
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David Miller - Feb. 11, 2009, 9:39 p.m.
From: Risto Suominen <risto.suominen@gmail.com>
Date: Wed, 11 Feb 2009 14:31:43 +0200

> As an interesting side effect, the patch caused my mesh module to stop
> working. It crashes.

I think you need to take this discussion to linuxppc-dev at this
point.

Nobody amongst the networking developers can say whether
your NOT_COHERENT_CACHE change is a valid or desirable
way to solve the problem, nor what side effects it might
have.
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Patch

Allow setting NOT_COHERENT_CACHE explicitly.

Signed-off-by: Risto Suominen <Risto.Suominen@gmail.com>
---
The testing is done on kernel version 2.6.24.

--- a/arch/powerpc/platforms/powermac/Kconfig.org	2008-01-25 00:58:37.000000000 +0200
+++ b/arch/powerpc/platforms/powermac/Kconfig	2009-02-10 17:44:24.000000000 +0200
@@ -18,4 +18,10 @@  config PPC_PMAC64
 	select PPC_970_NAP
 	default y
 
-
+config NOT_COHERENT_CACHE
+	bool "Incoherent cache"
+	default n
+	help
+	  Setting this option may be necessary for avoiding cache-related
+	  problems with some network cards on some platforms. An example is
+	  2104x and PowerMac 5500.